Some people thrive on it, some people hate it, but if you're working out and challenging your body, you'll definitely experience it: the day-after muscle soreness that makes you feel a little bit like you've been hit by a bus.
While it may be hard to sit after a circuit workout full of squats or you can't raise your arms to brush your hair a day after a killer tricep-sculpting session, DOMS, or delayed-onset muscle soreness, should be a suffered through with pride. That soreness means that you've worked muscles you may not be using regularly or challenged already strong muscles in a way that will build even more strength. Either way, the soreness happens because your muscles have been worked and are better for it. "You're basically tearing something and creating a micro trauma in the muscle," says celebrity trainer Harley Pasternak. "When the muscle recovers, it's going to recover stronger and denser than it was before."
While you may feel sore mere hours after a workout, DOMS usually peaks a day or two after a sweat session. It's nothing to worry about — in fact, you should be proud that you're building body-sculpting, calorie-burning muscles — but you should recognize the difference between a good kind of pain like DOMS and the type of pain that could signal an exercise-related injury. In general, all-over soreness or aches, especially well after your workout is over, is fine. If you feel a sharp pain or a burning sensation in any muscle group while you work out, however, you should stop exercising, rest, and seek out expert advice as soon as possible.